Current and future high frequency, e.g. millimetre wave, radio access technology (RAT) communication between nodes such as a radio base station and wireless communication devices, such as user equipment (UE), will heavily rely on antenna beam-forming (i.e. beam direction control and/or beam shape control). A reason for this is that it is desirable to attain acceptable path loss because of the typically small apertures of single antennas at the high radio frequencies involved, but also to compensate for the progressively reduced power capability of power amplifiers and increased noise figure of receivers as the frequency of operation is increased. Moreover, support for device-to-device (D2D) communication between several wireless communication devices using such high frequency RAT is an even more challenging problem as the need for beam forming is still valid while the wireless devices are often not stationary but moving.
However, it is to be noted that beam-forming involving narrow antenna beams leads to requirements on participating nodes or devices to be able to accurately track the antenna beams in order not to become a victim of the desired selectivity. That is, participating entities not being able to “see” each other due to misdirected antenna beams. This can be a severe problem even when participating nodes and/or devices move slowly in relation to each other in case the beams are very narrow.
In conventional prior art, beam tracking mechanisms are typically based on measurements using the transmission link between a radio base station (RBS) and a UE. Changes in received signal strength or signal to interference and noise ratio (SINR) metrics are used to identify the desired beam movement direction. However, a problem existing in conventional solutions is that the movement of UEs may be too fast to correct for in the UE only by tracking using measurements of received signal strength because these individual measurements are often noisy and need temporal smoothing. Needless to say, in a D2D scenario, there are two or more UEs communicating directly with each other while moving, which then aggravates the problem further.